The created buffers can be kept for later use, or be thrown away
immediately after use, depending on the value of this variable:

nil

Throw away as much as possible.

t

Keep everything.

1

Throw away buffers created for parsing, but keep the ones created for
lookup.

If a buffer is to be kept, the file is visited normally (which is
potentially slow but will happen only once). If a buffer is to be thrown
away, the initialization of the buffer depends upon the variable
reftex-initialize-temporary-buffers.

User Option:reftex-initialize-temporary-buffers

Non-nil means do initializations even when visiting file
temporarily. When nil, RefTeX may turn off find-file hooks and
other stuff to briefly visit a file. When t, the full default
initializations are done (find-file-hook etc.). Instead of
t or nil, this variable may also be a list of hook
functions to do a minimal initialization.

User Option:reftex-no-include-regexps

List of regular expressions to exclude certain input files from parsing.
If the name of a file included via \include or \input is
matched by any of the regular expressions in this list, that file is not
parsed by RefTeX.

User Option:reftex-enable-partial-scans

Non-nil means, re-parse only 1 file when asked to re-parse.
Re-parsing is normally requested with a C-u prefix to many RefTeX
commands, or with the r key in menus. When this option is
t in a multifile document, we will only parse the current buffer,
or the file associated with the label or section heading near point in a
menu. Requesting re-parsing of an entire multifile document then
requires a C-u C-u prefix or the capital R key in
menus.

User Option:reftex-save-parse-info

Non-nil means, save information gathered with parsing in files.
The file ‘MASTER.rel’ in the same directory as ‘MASTER.tex’ is
used to save the information. When this variable is t,

-
accessing the parsing information for the first time in an editing
session will read that file (if available) instead of parsing the
document.

-
exiting Emacs or killing a buffer in reftex-mode will cause a new
version of the file to be written.

User Option:reftex-parse-file-extension

File extension for the file in which parser information is stored.
This extension is added to the base name of the master file.

User Option:reftex-allow-automatic-rescan

Non-nil means, RefTeX may rescan the document when this seems
necessary. Applies (currently) only in rare cases, when a new label
cannot be placed with certainty into the internal label list.

User Option:reftex-use-multiple-selection-buffers

Non-nil means use a separate selection buffer for each label
type. These buffers are kept from one selection to the next and need
not to be created for each use - so the menu generally comes up faster.
The selection buffers will be erased (and therefore updated)
automatically when new labels in its category are added. See the
variable reftex-auto-update-selection-buffers.

User Option:reftex-auto-update-selection-buffers

Non-nil means, selection buffers will be updated automatically.
When a new label is defined with reftex-label, all selection
buffers associated with that label category are emptied, in order to
force an update upon next use. When nil, the buffers are left
alone and have to be updated by hand, with the g key from the
label selection process. The value of this variable will only have any
effect when reftex-use-multiple-selection-buffers is
non-nil.